The importance of developing a method for finding deposits of hydrocarbons in the ground with a high degree of accuracy cannot be questioned in these days of energy shortages. Typical location methods are described and claimed in U.S. Pat. Nos. 2,686,108 issued to Hoffmeister on Aug. 10, 1954, and entitled "Microfossil Prospecting for Petroleum" and 3,711,765 issued to Overton on Jan. 16, 1973, and entitled "Method of Locating Anomalous Zones of Chemical Activity in a Well Bore". The methods of these patents include measuring the microfossil content in boreholes drilled in the ground to locate ancient shorelines near where hydrocarbons deposits are commonly found and measuring the cationic potentials and redox potential of shale cuttings obtained from well bores, respectively.
Another method known in the art for locating hydrocarbon deposits is the use of explosives detonated within the ground to produce a seismic profile of the area being investigated to determine the existence of a geological formation suggesting the presence of hydrocarbons. Typically this method includes drilling a series of boreholes to a depth below the weathered zone with the boreholes being a uniform, predetermined distance from one another along a linear path. Explosives are then placed at the bottom of each borehole and detonated individually. Seismic devices on the ground above record the ground vibrations induced by the explosion. Upon the completion of data collection for the boreholes, a profile of the density under the ground may be plotted by combining the data, which may indicate the presence of a hydrocarbon reservoir.
Another method for locating hydrocarbon deposits is the use of geochemical data from the site under investigation. In this technique, sample holes are drilled typically to a depth of 5 feet below the surface. A sample is then taken from the bottom of the testhole and analyzed for the presence of the lighter hydrocarbons, C-1 through C-6. The presence of ethane (C-2) and propane (C-3) are taken as a definite indication of the presence of hydrocarbon reservoirs. In a similar manner, the type and concentration of certain bacteria may also indicate the presence of hydrocarbons.
Such prior art methods have suffered the shortcoming of only indicating one of a number of indications of the presence of hydrocarbons. A need has thus arisen for integrating or combining the data obtained by exploratory methods to more accurately and reliably predict the presence of hydrocarbons.